Cadmium, copper, cobalt, nickel, lead, and zinc in the water column of the Weddell Sea, Antarctica

Abstract

This paper presents results from the first complete investigation of the dissolved and suspended trace metals cadmium, copper, cobalt, nickel, lead, and zinc in the water column of the Weddell Sea, Antarctica. A total of 35 stations was covered in the central Weddell Sea and the shelf areas around the Filchner depression and Dronning Mauds Land. Snow samples were collected from the sea ice and from the Antarctic continent to evaluate the importance of the fresh water influence on the Weddell Sea. Oceanographic data, i.e., salinity, temperature, and nutrients, are used to link the trace metal results to the different water masses. The general range found is for cadmium, 0.5–0.8 nM; copper, 2.0–2.9 nM; cobalt, 20–40 nM; nickel, 6–7 nM; lead, 10 pM; zinc, 3–7 nM. The suspended trace metals are a small fraction, but considerably higher than in other oceans. The lowest concentrations of cadmium, copper, and zinc are found in the surface layer and in the whole water column at the Filchner Depression. Cobalt shows an increase in the surface water compared to the deep water. This is suggested to be generated by the terrogent material from the Antarctic continent from the melting of the ice. No evidence of anthropogenic lead can be seen in the lead profile. Nutrient trace metal relations found show poor statistical correlation in contrast to what is found in other oceans. This assumes that cadmium, copper, and zinc are not directly linked to the bioproduction cycle. However, the nutrient trace metal ratios found support the theory that the Weddell Sea is the ultimate source for generation of the nutrient trace metal ratios in the Pacific Ocean.